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ALEXANDER FLEMING (1881-1955): Alexander Fleming, a Scottish born physician who spent most of his time studying bacteria discovered the world’s first antibiotic known as “Penicillin” from the mould, Penicillium notatum. Fleming was an established pharmacologist and microbiologist who studied extensively on bacteriology, immunology and chemotherapy; and his series of experimentation and study led him to discovering the world’s first antibiotic substance known as benzylpenicillin (penicillin G). Though mankind has used a number of chemicals including herbs to treat infectious diseases since time immemorial, the astonishing discovery of penicillin (the first therapeutically used antibiotic) marked the beginning for the intensified exploration for other sources of antimicrobial agents even till date. Penicillin unlike other chemotherapeutic agents is a microbial product which can inhibit or kill susceptible microorganisms.


The discovery of penicillin by Fleming opened another era for chemotherapy and the use of antimicrobial agents to control infectious diseases. Penicillin was found to be the most effective chemotherapeutic agent against infectious diseases as at the time of its discovery before the development of resistance against the antibiotic. In 1928 Alexander Fleming streaked some plates of Staphylococcus aureus and left them to incubate until his return from a summer holiday he embarked on. In an unlikely set of circumstances, the beginning of the holiday was cold, and this allowed some contaminating mould spores that had blown in from a nearby window, and which was a ‘good and timely’ contaminant, to grow up on some of Fleming’s cultured plates. The increase in temperature encouraged the growth of the S. aureus. Normally, many experimenters when confronted with a contaminated plate will eventually look for the trash bin in order to repeat their experiment, but this was not the case for Alexander Fleming, who instead, spent some time to further examine the S. aureus culture plates. According to Louis Pasteur,CHANCE FAVOURS ONLY THE PREPARED MINDS IN THE FIELD OF OBSERVATION”.

Upon close examination, Fleming discovered that the fungus growing in his S. aureus plates had a zone of clearing around it where the Staphylococcus colonies would not grow. Fleming clearly guessed that the fungus was producing an antibacterial compound that had diffused into the medium, and which inhibited the growth of the S. aureus. Surprised by his findings, he cultured the fungus, a Penicillium mold, and eventually isolated a soluble extract that could kill or inhibit the growth of bacteria; and the compound was used to treat localized bacterial infections. Fleming later called the new compound penicillin. But due to limitations in the available technology as at the time, however, it was very difficult to prepare a solution that could be used throughout the body without causing problems. During World War II, the search for compounds that could fight infectious diseases increased as a result of increase in the number of wounded soldiers who died from life-threatening sepsis from infected wounds, and which was due to microbial colonization. This led Sir Howard Florey and Ernst Chain (both from Oxford University) to start a systematic study of antimicrobial compounds with the view of developing treatments for wounded soldiers. In their search, they ran into Alexander Fleming’s report which was written 9 years earlier, and this led them to develop methods for the industrial production and purification of penicillin in England in early 1940s.

Florey and Chain completed an important procedure which Fleming could not undertake as at the time he discovered penicillin (the “miracle drug”) due to some limitations in technological advancement. The availability of penicillin saved countless number of wounded soldiers in World War II. In 1945, Florey and Chain, and Fleming were awarded the Noble prize in Medicine and Physiology for their discovery of the world’s first antibiotic substance (penicillin). While Florey and Chain converted Fleming’s antimicrobial substance into a practical drug (penicillin) that was used to treat and cure some bacterial related infections as at the time including gonorrhea, it was Alexander Fleming who discovered the antimicrobial properties of the established antimicrobial substance, and thus named it penicillin. Though there is a global threat of microbial resistance to some available drugs, the discovery of antibiotics by Sir Alexander Fleming has continued to positively impact medicine even till date. And the continued rise in antibiotic resistant pathogens has stepped up the search for the discovery and development of novel and potent antimicrobial agents that will be less-amenable to microbial degradation or hydrolysis.  

Further reading

Brooks G.F., Butel J.S and Morse S.A (2004). Medical Microbiology, 23rd edition. McGraw Hill Publishers. USA. Pp. 248-260.

Madigan M.T., Martinko J.M., Dunlap P.V and Clark D.P (2009). Brock Biology of microorganisms. 12th edition. Pearson Benjamin Cummings Publishers. USA. Pp.795-796.

Nester E.W, Anderson D.G, Roberts C.E and Nester M.T (2009). Microbiology: A Human Perspective. Sixth edition. McGraw-Hill Companies, Inc, New York, USA.

Prescott L.M., Harley J.P and Klein D.A (2005). Microbiology. 6th ed. McGraw Hill Publishers, USA. Pp. 296-299.

Singleton P and Sainsbury D (1995). Dictionary of microbiology and molecular biology, 3d ed. New York: John Wiley and Sons.

Slonczewski J.L, Foster J.W and Gillen K.M (2011). Microbiology: An Evolving Science. Second edition. W.W. Norton and Company, Inc, New York, USA.


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